Inorganic encapsulant for electronic component with adhesion promoter

ABSTRACT

A package includes an electronic component, an inorganic encapsulant encapsulating at least part of the electronic component, and an adhesion promoter between at least part of the electronic component and the encapsulant.

TECHNICAL FIELD

Various embodiments relate generally to a package, a method ofmanufacturing a package, and a method of use.

BACKGROUND

A conventional package may comprise an electronic component mounted on achip carrier such as a leadframe, may be electrically connected by abond wire extending from the chip to the chip carrier, and may be moldedusing a mold compound as an encapsulant.

SUMMARY

There may be a need to encapsulate devices such as electronic componentswith a high reliability.

According to an exemplary embodiment, a package is provided whichcomprises an electronic component, an inorganic encapsulantencapsulating at least part of the electronic component, and an adhesionpromoter between at least part of the electronic component and theencapsulant.

According to another exemplary embodiment, a method of manufacturing apackage is provided, wherein the method comprises forming an adhesionpromoter on at least part of an electronic component, and at leastpartially encapsulating the electronic component with an inorganicencapsulant with the adhesion promoter in between (i.e. between at leastpart of the electronic component and the encapsulant).

According to another exemplary embodiment, an inorganic encapsulant isused for at least partially encapsulating a device with an adhesionpromoter between at least part of the device and the encapsulant.

According to an exemplary embodiment, the use of inorganic encapsulationmaterial for electronic components (such as semiconductor chips) hasturned out as technically highly advantageous, when an adhesion promoteris interposed between the electronic component and the inorganicencapsulant. Such an inorganic encapsulant may provide for a reliableelectric insulation, may have proper thermal properties and may providefor a mechanically robust surrounding of the electronic component. Bycovering at least part of the electronic component to be encapsulatedwith an adhesion promoter, the mechanical stability of the package maybe further increased and any tendency of delamination betweenencapsulant and electronic component may be strongly suppressed or eveneliminated.

In the following, further exemplary embodiments of the methods and thepackage will be explained.

In the context of the present application, the term “package” mayparticularly denote an electronic device comprising one or moreelectronic components packaged using an encapsulant. Optionally, also acarrier for the electronic component and/or one or more electricallyconductive contact elements (such as bond wires or clips) may beimplemented in a package.

In the context of the present application, the term “electroniccomponent” may in particular encompass a semiconductor chip (inparticular a power semiconductor chip), an active electronic device(such as a transistor), a passive electronic device (such as acapacitance or an inductance or an ohmic resistance), a sensor (such asa microphone, a light sensor or a gas sensor), an actuator (for instancea loudspeaker), and a microelectromechanical system (MEMS). However, inother embodiments, the encapsulated device may also be of differenttype, such as a mechatronic member, in particular a mechanical switch,etc.

In the context of the present application, the term “adhesion promoter”may particularly denote any material and/or measure enhancing adhesionbetween the electronic component and the encapsulant. More specifically,such an adhesion promoter (or coupling agent or bonding agent) may actas an interface between the inorganic encapsulant and the partially orentirely encapsulated electronic component or other device to enhanceadhesion between these two materials. Since such inorganic encapsulantmaterial on the one hand and the (in particular metallic and/orsemiconducting) encapsulated electronic component or other device on theother hand may be different concerning their physical and/or chemicalproperties (for instance chemical reactivity, surface properties, etc.),forming a direct strong adhesive bond between these two materials may bedifficult. An adhesion promoter may however act as a, in a chemicalsense, two-terminal interface providing a first connection terminal withthe encapsulant and providing a second connection terminal with theencapsulated electronic component or other device to chemically andphysically connect these dissimilar materials into a strong bondstructure (see also FIG. 2 ). More specifically, an adhesion promotermay act as a two-terminal, three-terminal or multi-terminal organicmolecule, such as aminosilanes that undergo prepolymerisation(oligomerisation) prior to application in their solution, for instancevia condensation reactions. In order to promote the adhesion between theone or more electronic components/devices and the inorganic encapsulant,the mentioned adhesion promoter may significantly promote mechanicalinterconnection between the mentioned constituents, so that themechanical and electrical reliability can be further improved.

In the context of the present application, the term “inorganicencapsulant” may particularly denote a material encapsulating the atleast one electronic component/device and comprising or consisting ofinorganic material. An inorganic material may be a chemical compoundthat lacks C—H bonds, i.e. a compound that is not an organic compound.

A gist of an exemplary embodiment is the use of an inorganicceramic-based encapsulation material for semiconductor devices or otherelectronic components. As examples for such an inorganic ceramic-basedencapsulation material, reference is made in particular to the ceramicformulations or materials described in Table 1.

Advantageously, a morphological adhesion promoter may be combined withan inorganic encapsulation material (for example concrete) that offersthe possibility to build highly reliable devices:

-   -   a) In more specific embodiments, self-passivating, only        self-passivating metals or highly stable metal oxides involved        for hermetic sealing of chips or other electronic components may        be used.    -   b) Advantageously, a corresponding package may be high        temperature stable up to 300° C. or higher, as there is no        organic material that may undergo decomposition.    -   c) Preferably, a porous morphological adhesion promotor, which        compensates a coefficient of thermal expansion (CTE)-mismatch,        may be implemented (compare also FIG. 14 and FIG. 15 ). In        particular a low-CTE ceramic encapsulant combined with such a        morphological adhesion promoter may lead to a significant stress        reduction or even stress minimization in the package.    -   d) Advantageously, strong package interfaces may be achieved        through mechanical interlocking dendrites or the like, so that        preferably no delamination of the ceramic encapsulation occurs        during the entire lifetime of the package.

Also advantageously, a material as described herein may be used, whereina corresponding adhesion promoter comprises or consists of a roughenedor structured surface or has a porous or dendrite-like structure.Examples are given in Table 3. A corresponding adhesion layer may alsoact advantageously as a CTE adaption layer.

Further preferred is the use of materials as described herein with anadditional layer adjacent to the encapsulation material, which can forexample comprise or consist of polymers, gels, inorganic layers, organiclayers or gases (for example air, nitrogen).

The use of III/IV semiconductors (for instance GaN), of III/Vsemiconductors, and/or of wide band gap semiconductors, which may allowhigher junction temperature Tj as well as the requirements for longerlife time from automotive for self-driving cars lead to the demand ofpackages that are reliable at higher temperatures and achieve longerlifetime. Since current packaging solutions are either not applicablefor higher temperatures (for example epoxy systems may be limited toabout 200° C.) and/or involve an excessive effort, the need ofalternative package solutions is emerging. Exemplary embodiments providea solution for this conventional shortcoming.

In an embodiment, the encapsulant is a ceramic-based encapsulant. In thecontext of the present application, the term “ceramic” may particularlydenote a technical ceramic. Such technical ceramics may have theproperties according to ENV 12212 (in the most recent version at thepriority date of the present application). In particular, the ceramicmay be a highly developed, high-performance applicable ceramic material,which may be mainly non-metallic and inorganic and may have certainfunctional properties. In particular, the term “ceramic” in the scope ofthis disclosure may encompass all listed ceramic types of ENV 12212: C111, C 112, C 120, C 130, C 140, C 210, C 221, C 221, C 230, C 240, C250, C 410, C 420, C 430, C 440; C 510, C 511, C 512, C 520, C 530, C610, C 620, C 310; C 320, C 330, C 331, C 340, C 350, C 351, C 780, C786, C 795, C 799, RBAO (denoting a term according to DIN ENV 14 242), C810, C 820, MgO (denoting a term according to DIN ENV 14 242), PSZ(denoting a term according to DIN ENV 14 242), FSZ (denoting a termaccording to DIN ENV 14 242), TZP (denoting a term according to DIN ENV14 242), ATI (denoting a term according to DIN ENV 14 242), PZT(denoting a term according to DIN ENV 14 242), SiO2 (denoting a termaccording to DIN ENV 14 242), TiO2 (denoting a term according to DIN ENV14 242). Also, Spinel or Mullite materials, both denoting commonly usedengineering terms, may be covered by the term “ceramic”. According tothe presently described exemplary embodiment, a ceramic-based inorganicmaterial is used for encapsulating one or more electronic components ofa package partially or entirely. It has turned out that a ceramicmaterial has excellent properties in terms of encapsulating chips andother electronic components. Firstly, ceramic materials are reliablyelectrically insulating and mechanically robust so as to provide anexcellent mechanical and electrical protection of the encapsulatedelectronic component. At the same time, the adhesion between electroniccomponent and ceramic encapsulant can be rendered very stable, inparticular when an adhesion promoter is sandwiched in between.Furthermore, also the properties in terms of a correspondence between acoefficient of thermal expansion of the ceramic encapsulant and acoefficient of thermal expansion of the electronic component may bereasonably small so that the thermal stress in an interior of thepackage can be kept sufficiently small to maintain integrity of thepackage even in the presence of extensive thermal cycles duringlong-term use.

In an embodiment, the ceramic-based encapsulant comprises at least oneof the group consisting of cement, concrete, gypsum, and mortar. Thementioned materials show excellent properties in terms of encapsulatingelectronic components and are therefore highly appropriate for thementioned use. In particular, a cement-based encapsulant may be highlyadvantageous for this purpose.

In another embodiment, the encapsulant is an inorganic (i.e. notcomprising organic carbon) polymer-based encapsulant, such as a siliconpolymer (i.e. an inorganic polymer comprising silicon) or an aluminumpolymer (i.e. an inorganic polymer comprising aluminum). Inorganicpolymers may denote polymers with a skeletal structure that does notinclude carbon atoms in the backbone.

In an embodiment, the adhesion promoter of the package is amorphological adhesion promoter, i.e. an adhesion promoter having amorphological structure. Correspondingly, the manufacturing method maycomprise forming an adhesion promoter, in particular a morphologicaladhesion promoter, on the electronic component before the encapsulating.In the context of the present application, the term “morphologicalstructure” may particularly denote a structure having a topology and/orporous structure and/or being shaped in such a way so as to increase theconnection surface with connected material of encapsulant and/orelectronic component to thereby promote adhesion. Moreover, themorphology of a morphological adhesion promoter may cause anadvantageous mechanical interlocking between material of encapsulantand/or electronic component on the one hand and material of themorphological adhesion promoter on the other hand. In other words, amorphological structure promotes adhesion due to its shape, rather thanonly promoting adhesion due to its chemistry. However, it is alsopossible that a morphological structure is synergistically made ofmaterial which, in view of its intrinsic properties, promotes adhesionadditionally to the shape. In particular, a morphological adhesionpromoter may be an inorganic porous material. For instance, the presenceof a morphological structure between electronic component andcement-based encapsulant may additionally promote the interconnectionbetween semiconductor chip and encapsulant so as to further improvereliability. Highly advantageously, the adhesion promoter may promoteadhesion at least partially as a result of its morphology. Thus, aspecific shaping and in particular increase of the interior surface ofthe adhesion promoter may enhance adhesion between chip and encapsulant,mediated by the morphological adhesion promoter.

In an embodiment, the morphological adhesion promoter comprises at leastone of the group consisting of a metallic structure, an alloy structure,a chromium structure, a vanadium structure, a molybdenum structure, azinc structure, a manganese structure, a cobalt structure, a nickelstructure, a copper structure, a flame deposited structure, a roughenedmetal structure (in particular a roughened copper structure or aroughened aluminum oxide structure), and any oxide, nitride, carbide,and selenide of any of said structures. All structures may comprise orconsist of these metals and/or the alloys thereof. In addition, thesestructures may comprise or consist of these metals and theiralloy-oxides. In particular, single oxides and mixed oxides are possiblein different embodiments. Whether the alloy oxidizes or not may dependon the thermal budget in production. However, other materials andstructures may be used for the morphological adhesion promoter as well(see also FIG. 3 to FIG. 13 ). The above-mentioned flame depositedstructure may comprise or consist of silicon dioxide, any titanium oxide(such as for instance TiO₂, TiO, Ti_(x)O_(y)), etc. Any organometallicprecursor can be used that can be burned in a mixture with a burning gassuch as propane or butane and form the specific metal oxide.

In particular, a morphological adhesion promoter may be formed usingAtomic Layer Deposition (ALD), Chemical Vapor Deposition (CVD), etc.

In another embodiment, the adhesion promoter is an organic adhesionpromoter, such as silane. Such an organic adhesion promoter may promoteadhesion in view of its chemical properties.

In an embodiment, the (in particular morphological) adhesion promoterhas a plurality of openings. Such openings may have an orderedstructure, as for instance in the presence of a layer being patterned inaccordance with a well-defined mask. Such a mask may have a regulararray of openings which translates into a regular array of openings inthe morphological adhesion promoter. However, it is also possible andeven preferred when the openings of the morphological adhesion promoterhave a non-ordered, in particular arbitrary or random character. Thiscan be achieved for instance by a non-specific etching processgenerating a random arrangement of openings for increasing the surfaceand promoting interlocking.

In an embodiment, the openings comprise at least one of the groupconsisting of pores, dendrites, and gaps between islands of a patternedstructure. However, other kinds of openings can be formed as well aslong as they increase the surface of the morphological adhesion promoterand promote mechanical interlocking between material of the adhesionpromoter and material of the encapsulant. For instance, an adhesionpromoter layer may comprise or consist of plates with 10 nm to 500 nmsize, for example hexagonal, round shape and in multiple angleorientation forming a microscopic porous surface with a pore size in therange of 10 nm to 500 nm. The surface of the plates may be additionallycovered with a sponge of a porous layer of 10 nm to 100 nm with a muchlower pore size in the range of 1 nm to 100 nm.

In an embodiment, a material of the adhesion promoter is adapted for atleast partially compensating a mismatch of the coefficient of thermalexpansion (CTE) between a material of the electronic component and amaterial of the encapsulant. Highly advantageously, the adhesionpromoter not only serves for enhancing adhesion between electroniccomponent and inorganic encapsulant by promoting mechanicalinterlocking, but may at the same time provide a smooth transition ofthe CTE value between electronic component (in particular a pad thereof)and the inorganic encapsulant. Without the adhesion promoter, a suddenjump of the CTE value may occur at an interface between electroniccomponents (in particular a semiconductor chip with metal pad) and theinorganic (in particular ceramic) encapsulant in view of the differentmaterials (ceramic, metal, semiconductor) of encapsulant and electroniccomponent. However, when the morphology and/or the material of theadhesion promoter is configured so as to provide a CTE gradient inbetween the CTE values of the inorganic encapsulant and the material ofthe electronic component, a smooth transition may be achieved and theformation of mechanical stress in an interior of the package in theevent of rapidly changing temperatures can be suppressed. In particular,it is possible that the morphology of the adhesion promoter contributesto a smooth or even continuous transition of the CTE value. When forinstance the cross-sectional area of the openings in the adhesionpromoter decreases from the encapsulant towards the electroniccomponent, the amount of material of the encapsulant inside of suchopenings may gradually decrease spatially from the pure encapsulanttowards a surface of the electronic component. Thus, also the morphologyof the adhesion promoter may contribute to a smooth transition of theCTE value, so as to further increase mechanical reliability of thepackage.

In an embodiment, the adhesion promoter forms an interlayer in aninterface region between the encapsulant and the electronic component.In particular, a porous interlayer may provide a (in particularcontinuous) transition of porosity between the encapsulant and theelectronic component. In the context of the present application, theterm “porosity” may denote a ratio between a pore volume and a totalvolume (i.e. a sum of the pore volume and a solid material volume) of aporous body such as the morphological interlayer. Thus, a separate layerwith spatially varying porosity may be interposed between electroniccomponent and encapsulant and may serve as adhesion promoter withgradually varying physical properties. The material of such aninterlayer may be selected so as to further improve adhesion, reduce aCTE mismatch, etc. For this purpose, it is for instance possible thatthe pores of the interlayer are at least partially filled with materialof the encapsulant. In combination with the spatially varying porosityof the interlayer, this may result in a gradual CTE transition.

Preferably, the interlayer has a thickness in a range between 30 nm and500 nm, in particular in a range between 50 nm and 200 nm. for instance,the thickness of the interlayer may be about 100 nm. Over the thicknessof the adhesion promoter interlayer, porosity (i.e. the ratio betweenpore volume on the one hand and the sum of pore volume and solid volumeon the other hand) may be decreased for example from 90% (close to aninterface to the encapsulant) to 10% (close to the interface of theelectronic component).

In an embodiment, the interlayer comprises at least one of the groupconsisting of a polymer, a gel, an inorganic layer, an organic layer,and at least one gas, a particular air or nitrogen. However, othermaterials may be used as well.

In an embodiment, the (in particular ceramic-based) inorganicencapsulant has inherently non-flammable properties. Thus, in view ofsuch intrinsic non-flammable properties of the inorganic encapsulant,the encapsulant may be free of non-flammable additives. Advantageously,the ceramic material of the encapsulant itself may have non-flammableproperties so that the addition of an additive with non-flammableproperties may be omitted in the encapsulant. As a result, thecomposition of the encapsulant may be rendered simple, so thatencapsulation of the one or more electronic components can beaccomplished with reduced effort.

In an embodiment, the method comprises forming the encapsulant byproviding a mixture of a solution and filler particles in the solution,as a precursor for forming the finally solid encapsulant. In the contextof the present application, the term “solution” may particularly denotea liquid or flowable medium, and/or a slurry. In the context of thepresent application, the term “filler particles” may particularly denotea (in particular powderous or granulate-type) substance filling outinterior volumes in the matrix. By the selection of the filler, thephysical and/or chemical properties of the encapsulant can be adjusted.Such properties may include the coefficient of thermal expansion, thethermal conductivity, the dielectric properties, etc. The mixture ofsolution and filler particles may translate, after curing, into anencapsulant composed of a matrix of ceramic material with (ceramic ornon-ceramic) filler particles within this solid matrix. The matrix mayprovide a robust constituent of the encapsulant and may ensuremechanical integrity. The filler particles may be optionally added so asto fine tune the physical, chemical, etc. properties of the encapsulant.For instance, the filler particles may increase thermal conductivity ofthe encapsulant so as to efficiently remove heat out of an interior ofthe package (such heat may be generated by the electronic component, forinstance when embodied as power semiconductor chip). It is also possiblethat the filler particles provide an improved dielectric decouplingbetween the electronic component and the surrounding of the package.

In an embodiment, the method comprises providing the solution with anon-aqueous solvent, in particular an alcohol. Thus, the liquid phasemay be different from an aqueous solvent in order to make it possible tocontrol the reaction kinetics. However, alternatively, the liquid phasemay also comprise or consist of water.

In an embodiment, the method comprises contacting the morphologicaladhesion promoter with the solution as one of precursors of theencapsulant in such a way that the solution penetrates into openings inthe morphological adhesion promoter. With such a manufacturingprocedure, it is possible that the liquid precursor material of theencapsulant efficiently inserts into openings of the morphologicaladhesion promoter on the one or more electronic components. After curingand solidifying the precursor material of the encapsulant, the openingsmay remain permanently filled with encapsulant material. As a result, asmooth transition of the CTE value and/or of other physical and/orchemical properties between the inorganic (in particular ceramic)encapsulant and the electronic component (in particular a semiconductorchip with metal pads) may be accomplished. After curing, the liquidprecursor solidifies and permanently remains within the openings so asto establish a smooth transition of the properties between chip andencapsulant.

In an embodiment, the encapsulant further comprises at least oneadditive. In particular, such at least one additive may have a maximumweight percentage, based on the total weight of the encapsulant, of lessthan 5 weight percent, in particular less than 1 weight percent. Withthe addition of one or more additives, the specific properties of theencapsulant can be adjusted in accordance with a desired application.

In an embodiment, the at least one additive is selected from a groupconsisting of a pigment, a stress modifier, an ion capturer and arelease agent. The addition of a pigment may allow to adjust the colorof the encapsulant. For instance, the encapsulant may be renderedintransparent so as to avoid any undesired interaction between light andan electronic component encapsulated within the encapsulant. By theaddition of a stress modifier, the thermal stress in an interior of apackage in form of an encapsulated electronic component may be adjusted.An ion capturer may capture charged particles in an interior of apackage or package so as to ensure a proper electric insulation of theencapsulant. The provision of a release agent may promote the simplerelease of a cured encapsulant out of an encapsulation tool.

In an embodiment, the filler particles are selected from a groupconsisting of crystalline silica, fused silica, spherical silica,titanium oxide, aluminium hydroxide, magnesium hydroxide, zirconiumdioxide, calcium carbonate, calcium silicate, talc, clay, carbon fiber,glass fiber and mixtures thereof. Other filler materials are howeverpossible depending on the demands of a certain application. Fillerparticles (for example SiO₂, Al₂O₃, Si₃N₄, BN, AlN, diamond, etc.), forinstance for improving thermal conductivity may be embedded in theencapsulant. However, other filler particles may be implemented in theencapsulant as well, in addition or alternatively to the mentionedfiller particles. In particular, organic particles may be used asfillers (for instance, fillers can also comprise or consist of polymersor polymer mixtures, such as: epoxies, polyethylene, polypropylene,etc.). Also, it should be mentioned that the filler can be treated in away to improve the adhesion between the filler and the encapsulantcomprising the filler. Filler coatings can be of the group of silanes,thiols, or porous structures. Also, porous fillers can be used. Inparticular, filler particles may be provided as nanoparticles ormicroparticles. Filler particles may have identical dimensions or may beprovided with a distribution of particle sizes. Such a particle sizedistribution may be preferred since it may allow for an improved fillingof gaps in an interior of the encapsulant. For instance, a dimension ofthe filler particles may be in the range between 1 nm and 200 μm, inparticular in a range between 10 nm and 20 μm, more particularly in arange between 2 μm and 5 μm. For instance, the shape of the fillerparticles may be randomly, spherical, cuboid-like, flake-like, andfilm-like. The filler particles can be modified, coated, and/or treatedas to improve the adhesion and/or the chemical binding to thesurrounding matrix. Examples are silanes. A coating can also change thesurface energy of the fillers and may thereby improve and enable thewetting of the solution/the matrix.

In an embodiment, the package comprises a carrier on which theelectronic component is mounted. For instance, such a carrier may be aleadframe (for instance made of copper), a DAB (Direct AluminumBonding), DCB (Direct Copper Bonding) substrate, etc. Also at least partof the carrier may be encapsulated by the encapsulant, together with theelectronic component. The mentioned carrier may have a metallic surfacewhich may be prone to corrosion. However, when using an inorganicencapsulant in combination with an adhesion promoter, the carrier may beencapsulated in the encapsulant without the risk of corrosion.

Preferably, also the carrier can be at least partially covered by anadhesion promoter as described herein before being at least partiallyencapsulated by an encapsulant as described herein. This may furtherimprove mechanical reliability of the package. In other words, allembodiments relating to the adhesion promoter and all embodimentsrelating to the encapsulant and described in detail for the electroniccomponent apply also to the carrier.

In an embodiment, the package comprises an electrically conductivecontact element electrically coupling the electronic component with thecarrier. For instance, the electrically conductive contact element maycomprise a clip, a wire bond, and/or a ribbon bond. A clip may be athree-dimensionally bent plate type connection element which has twoplanar sections to be connected to an upper main surface of therespective electronic component and an upper main surface of the chipcarrier, wherein the two mentioned planar sections are interconnected bya slanted connection section. As an alternative to such a clip, it ispossible to use a wire bond or ribbon bond which is a flexibleelectrically conductive wire or ribbon shaped body having one endportion connected to the upper main surface of the respective chip andhaving an opposing other end portion being electrically connected to thechip carrier.

Preferably, also the carrier can be at least partially covered by anadhesion promoter as described herein before being at least partiallyencapsulated by an encapsulant as described herein. This may furtherimprove mechanical reliability of the package. In other words, allembodiments relating to the adhesion promoter and all embodimentsrelating to the encapsulant and described in detail for the electroniccomponent apply also to the carrier.

In an embodiment, the method comprises pre-treating at least part of theelectronic component, carrier and/or electrically conductive contactelement for promoting adhesion between the encapsulant and at least partof the electronic component, carrier and/or electrically conductivecontact element. Thus, the adhesion between the above-describedencapsulant and the electronic member may be improved by applying anadhesion promoting additional device-level treatment. Highlyadvantageously, it is possible to pre-treat the package or part thereof(for instance a metallic surface thereof) so as to improve its adhesionproperties with regard to the above-described encapsulant. For instance,it is possible to roughen the surface of the package or part thereofbefore encapsulation by the encapsulant. Such a roughening may becarried out mechanically (for instance by grinding), chemically, by alaser treatment, etc. It is also possible to carry out a surfaceactivation of the surface of the package or part thereof to beencapsulated by the encapsulant. Such a surface activation may beaccomplished, for instance, by a plasma treatment of the respectivesurface, in particular of the respective metallic surface.

In an embodiment, the package is configured as one of the groupconsisting of a leadframe connected power module, a Transistor Outline(TO) package, a Quad Flat No Leads Package (QFN) package, a SmallOutline (SO) package, a Small Outline Transistor (SOT) package, and aThin Small Outline Package (TSOP) package. Also, packages for sensorsand/or mechatronic devices are possible embodiments. Moreover, exemplaryembodiments may also relate to packages functioning as nano-batteries ornano-fuel cells or other devices with chemical, mechanical, opticaland/or magnetic actuators. Therefore, the package according to anexemplary embodiment is fully compatible with standard packagingconcepts (in particular fully compatible with standard TO packagingconcepts) and appears externally as a conventional package, which ishighly user-convenient.

In an embodiment, the package is configured as power module, forinstance molded power module. For instance, an exemplary embodiment ofthe package may be an intelligent power module (IPM). Another exemplaryembodiment of the package is a dual inline package (DIP).

In an embodiment, the electronic component is configured as a powersemiconductor chip. Thus, the electronic component (such as asemiconductor chip) may be used for power applications for instance inthe automotive field and may for instance have at least one integratedinsulated-gate bipolar transistor (IGBT) and/or at least one transistorof another type (such as a MOSFET, a JFET, etc.) and/or at least oneintegrated diode. Such integrated circuit elements may be made forinstance in silicon technology or based on wide-bandgap semiconductors(such as silicon carbide). A semiconductor power chip may comprise oneor more field effect transistors, diodes, inverter circuits,half-bridges, full-bridges, drivers, logic circuits, further devices,etc.

In an embodiment, the electronic component experiences a verticalcurrent flow. The package architecture according to exemplaryembodiments is particularly appropriate for high power applications inwhich a vertical current flow is desired, i.e. a current flow in adirection perpendicular to the two opposing main surfaces of theelectronic component, one of which being used for mounting theelectronic component on the carrier.

As substrate or wafer forming the basis of the electronic components, asemiconductor substrate, in particular a silicon substrate, may be used.Alternatively, a silicon oxide or another insulator substrate may beprovided. It is also possible to implement a germanium substrate or aIII-V-semiconductor material. For instance, exemplary embodiments may beimplemented in GaN or SiC technology.

Furthermore, exemplary embodiments may make use of standardsemiconductor processing technologies such as appropriate etchingtechnologies (including isotropic and anisotropic etching technologies,particularly plasma etching, dry etching, wet etching), patterningtechnologies (which may involve lithographic masks), depositiontechnologies (such as chemical vapor deposition (CVD), plasma enhancedchemical vapor deposition (PECVD), atomic layer deposition (ALD),sputtering, etc.).

The above and other objects, features and advantages will becomeapparent from the following description and the appended claims, takenin conjunction with the accompanying drawings, in which like parts orelements are denoted by like reference numbers.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of exemplary embodiments and constitute a part of thespecification, illustrate exemplary embodiments.

In the drawings:

FIG. 1 illustrates a cross-sectional view of a package according to anexemplary embodiment to be mounted on a mounting structure.

FIG. 2 schematically illustrates an interface region with amorphological adhesion promoter between an electronic component and aninorganic ceramic-based encapsulant according to an exemplaryembodiment.

FIG. 3 is a plan view of a morphological adhesion promoter according toan exemplary embodiment comprising manganate.

FIG. 4 is a plan view of a morphological adhesion promoter according toan exemplary embodiment comprising zinc-chromium alloy.

FIG. 5 is a cross-sectional view of the morphological adhesion promoteraccording to FIG. 4 .

FIG. 6 is a plan view of a morphological adhesion promoter according toan exemplary embodiment comprising zinc vanadium alloy and oxide.

FIG. 7 is a cross-sectional view of the morphological adhesion promoteraccording to FIG. 6 .

FIG. 8 is a plan view of a morphological adhesion promoter according toan exemplary embodiment comprising zinc molybdenum alloy and oxide.

FIG. 9 is a plan view of a morphological adhesion promoter according toan exemplary embodiment comprising zinc-vanadium.

FIG. 10 is a cross-sectional view of the morphological adhesion promoteraccording to FIG. 9 .

FIG. 11 shows a detail of the cross-sectional view of FIG. 10 .

FIG. 12 shows a detail of the cross-sectional view of FIG. 11 .

FIG. 13 shows a further detail of the morphological adhesion promoteraccording to FIG. 9 to FIG. 12 which shows a zinc vanadium seed layer asa starting layer for the final porous adhesion promoter layer.

FIG. 14 illustrates a model of a porous morphological adhesion promoteraccording to an exemplary embodiment.

FIG. 15 is a diagram illustrating a stress mean value along the verticaldirection of the porous morphological adhesion promoter according toFIG. 14 .

FIG. 16 is a diagram illustrating a stress mean value along the verticaldirection without porous morphological adhesion promoter, for comparisonwith FIG. 15 .

DETAILED DESCRIPTION

The illustration in the drawing is schematically and not to scale.

Before exemplary embodiments will be described in more detail referringto the figures, some general considerations will be summarized based onwhich exemplary embodiments have been developed.

According to exemplary embodiments, an encapsulant is providedcomprising or consisting of an inorganic material—in particular ceramics(for example concrete)—combined with a—preferably morphological—adhesionpromoter.

Existing epoxy-based molding compounds have very high coefficients ofthermal expansion (CTE) with limited yield strength. In addition, thesethermosets may tend to crack along interfaces and in bulk. Furthermore,delamination at the interface may happen in such conventionalapproaches.

Moreover, besides mechanical and thermomechanical limitations, existingpolymer based encapsulation may have a limitation regarding thermaldegradation and may start to degrade already at very low temperature of200° C. Specific semiconductor materials (such as GaN, SiC or modernMOSFET generations) may however require much higher temperaturestability of the respective package of up to 300° C. which cannot beachieved with conventional encapsulation materials, for exampleepoxy-based polymeric encapsulants.

Conventional epoxy mold compounds may have inorganic fillers (forexample SiO₂) with high filler contents to reduce the CTE value of thebulk material. To increase the adhesion of the mold compound towards asemiconductor chip, leadframe and other interfaces, various adhesionpromoter molecules may be added. In addition to the adhesion promoters,these mold compounds may comprise various different chemicals, such asflame-retardants. However, possible reactions between the differentcomponents at higher temperatures may lead to additional chemicalspecies that may be dangerous for the package.

Limitations of conventional encapsulants based on hydrocarbon-basedencapsulation materials (epoxy, etc.) include their limited yieldstrength, high CTE and low temperature resistance, as such materials maydecompose quickly at higher temperature.

In order to overcome at least part of the above-mentioned and/or othershortcomings, an exemplary embodiment uses an inorganic encapsulationmaterial, in particular a ceramic encapsulation material. Usingceramic-based inorganic materials (for example concrete) may offer amuch lower CTE at much higher yield strength. Since concrete materialsmay be non-flammable non-polymers, additives such as flame retardantscan be omitted, thus reducing the complexity of the encapsulationmaterial. Additionally, concrete offers a far broader stability when itcomes to higher temperatures of more than 300° C. Conventional moldcompounds already show stability weakness at 200° C. Details of ceramicformulations of encapsulants used according to an exemplary embodimentsand their solidification mechanism are shown in Table 1 below.

TABLE 1 Table 1: Overview of ceramic formulations and inorganic polymerformulations and their different phases to interact with any of theadhesion promoters described in Table 3 Solid phase Liquid matrixSolidification Material phase in bulk of liquid phase Additives ConcreteSoluble Al₂O₃, Formation of Concrete Ca-oxide SiO₂, hydrates of23iquefier, and Si-oxde Fe₂O₃ Ca-oxide, Super- phases Ca- plasticizer,(for example Aluminates, Stabilizer, Ca(OH)₂; Ca-Silicates Airtrapmaximum former, concentration Accelerator 1.7 g/L in for water atsolidifica- 20° C.) (*1) tion: CaCl₂, carbonate, Na₂CO₃, aluminate,Tricalcium- aluminate, Inhibitor, Sealing agents Gypsum Soluble Ca-Formation of Ca-sulfate sulfate Ca-sulfate and its hydrates hydrateshydrates (for example CaSO₄; maximum concentration 2 g/L in water) (*1)Mortar Soluble CaCO₃, Formation of Ca-oxide CaOH hydrates of andSi-oxide and Ca-oxide, phases its further (for example hydridessolidifycation Ca (OH) ₂; with absorption maximum of CO₂: concentrationCa(OH)₂ + 1.7 g/L in CO₂ −> CaCO₃ + water at H₂O 20° C.) (*1) SiliconSilicate polymer Aluminum Aluminate polymer ((*1): Solvents: Besideswater also alcohols and/or other solvents may be used)

Table 2 shows different types of cements which may be used asceramic-based encapsulant of a package of an exemplary embodiment.

TABLE 2 Table 2: Examples for cement components used for concreteformulations Portland Siliceous Calcareous Slag Silica Property cementfly ash fly ash cement fume Silicon 21.9 52 35 35 85 to 97 oxide content(%) Aluminum 6.9 23 18 12 oxide (%) Iron 3 11 6 1 oxide (%) Calcium 63 521 40 <1 oxide (%) Magnesium 2.5 oxide (%) SO₃ (%) 1.7

Using a morphological adhesion promoter as a base for the ceramicencapsulation material may allow for efficiently improving intra-packageadhesion within a package according to an exemplary embodiment.

In embodiments, the ceramic based materials may be manufactured andprocessed as a mixture of solution and particles to encapsulate theelectronic component(s). To ensure a proper interaction between theencapsulation material and a morphological adhesion promoter, themorphological adhesion promoter may be preferably applied before theapplication of the encapsulation material.

At the time when the liquid encapsulation material is getting contact tothe morphological adhesion promoter, the liquid part of the mixture,during application on the electronic component, may be able to penetrateinto pores of the adhesion promoter layer. Possible morphologicaladhesion promoters which may be used according to exemplary embodimentsare shown in Table 3. For all these morphological adhesion promoters thegiven pore sizes and layer thickness can be adapted to the respectiveencapsulation material by correspondingly adjusting deposition processparameters.

Again referring to Table 3, the chromium, vanadium and molybdenum-basedadhesion promoters may be formed by galvanic deposition of thecorresponding inorganic material. Thus, the three mentioned adhesionpromoters are all an inorganic morphological adhesion promoters with asponge-like pore structure. A flame deposited adhesion promoter may be aporous silicon oxide layer deposited from a gas phase, for instanceusing a flame, and is also a morphological adhesion promoter. Roughcopper can be created by a corresponding copper etching procedure of acopper layer which causes porosity of the surface of the etched copperlayer, thereby producing this morphological copper-based adhesionpromoter. In a similar way, aluminum oxide may be roughened. Such analuminum oxide material may be formed by thermal oxidation of aluminumor by ALD (atomic layer deposition). What concerns a wet chemicaletching process for an ALD layer, it should be mentioned that this isonly an exemplary way of getting the layer porous. For instance, watervapor can be already enough to get the porous layer. In addition,aluminium oxide may be formed porous by Chemical Vapor Deposition (CVD)with specific gas composition of aluminium organyl in the chamber. Apartfrom this, also silicon nitride can be deposited porous with a specificratio between TEOS (tetraethylsilane) and ammonia (NH₃) and specificdeposition conditions regarding concentration and temperature. By asubsequent wet etching procedure, the created aluminum oxide may berendered porous, wherein the pores may for instance have a substantiallycolumnar and/or substantially spherical shape.

As an alternative to the mentioned inorganic morphological adhesionpromoters, it is also possible to use an organic adhesion promoter, forinstance silane.

A liquid precursor or a liquid part of the encapsulation material maycrystalize in a sponge layer or in pores of a morphological adhesionpromoter through formation of a solid phase, for example for concreteformation of crystalline hydrates.

During this solidification of the liquid phase in the porousmorphological adhesion promoter sponge, the morphological adhesionpromoter and the encapsulation material may form a mixture offiber/encapsulation interlayer. Besides a strong adhesion, thisinterlayer enables a CTE adaption from the electronic component, carrieror substrate to the encapsulation material. The ratio between adhesionpromoter volume fraction and encapsulation material volume fraction maycontinuously change within the formed interlayer. The average CTE of thenano-structured layer may change from CTE (electronic component, carrieror substrate) to CTE (encapsulation material) continuously, depending onthe pore size and the porosity. Therefore, the formed interlayer (whichmay be composed of material of the morphological adhesion promoter andmaterial of the encapsulant, with spatially varying percentages) mayform a layer with a continuous change of the CTE value from theelectronic component or device substrate to the encapsulation material.A CTE mismatch between electronic component or device substrate on theone hand and encapsulation material on the other hand, which maygenerate stress (in particular thermomechanical stress), may bepartially or even entirely compensated. Together with the advantageouslylow-CTE characteristic of a ceramic encapsulation, this may lead tostress reduction or even minimization in the package.

Besides adhesion promotion and stress reduction, the morphologicaladhesion promoter may also act as a corrosion barrier. Especiallytogether with the ceramic encapsulation, the formed interlayer may actas a protection from water and oxygen.

In particular in case of a morphological adhesion promoter using Cr, V,or Mo, the adhesion to the device surface can be made also via a seedlayer of the actual adhesion promoter layer as a metallurgical contact.Such a seed layer may also act as a corrosion barrier.

Table 3 shows an overview of morphological adhesion promoters which maybe used according to exemplary embodiments:

TABLE 3 Table 3: Overview of morphological adhesion promoters that mayinteract with liquid-phase encapsulation materials (other materials arepossible in other embodiments, in particular: a metallic structure, analloy structure, a chromium structure, a vanadium structure, amolybdenum structure, a zinc structure, a manganese structure, a cobaltstructure, a nickel structure, a copper structure, a flame depositedstructure, a roughened metal structure, in particular a roughened copperstructure or a roughened aluminum oxide structure, and any oxide,nitride, carbide, and selenide of said structures) Adhesion MaterialPore Layer Preparation/deposition promoter of layer size thicknessprocess Cr ZnCr-oxide 1-500 nm 1-500 nm Galvanic and and ZnCr-electroless alloy deposition with including pulse plating and seed layerplating, or V ZnV-oxide 1-500 nm 1-500 nm constant current and ZnV-alloy including seed layer Mo ZnMo-oxide 1-500 nm 1-500 nm and ZnMo-alloy including seed layer Flame SiO₂, 1-500 nm 1-500 nm Flame or plasmadeposited Si—O—C deposition with precursors (*1) Rough Cu Etched Cu1-500 nm 1-500 nm Anisotropic etching surface of Cu or its alloys atfrom grain boundaries (*2) various Cu alloys Al₂O₃ Al₂O₃ 1-500 nm 1-500nm Thermal oxidation rough of aluminum or deposition of Al₂O₃ from, gasphase (atom layer deposition); treatment with aqueous solutions to formsponge and dendrites (*1): Precursors: Tetraethylsilane,Hexamethyldisiloxane, Hexamethyldisilane, Ti-organyls (*2): Example Curoughening with H₂SO₄/H₂O₂ etching with benzotriazole additive toenhance selectivity of etching to grain boundaries

FIG. 1 illustrates a cross-sectional view of a package 100, which isembodied as a Transistor Outline (TO) package, according to an exemplaryembodiment. The package 100 is mounted on a mounting structure 132, hereembodied as printed circuit board, for establishing an arrangement 130.

The mounting structure 132 comprises an electric contact 134 embodied asa plating in a through hole of the mounting structure 132. When thepackage 100 is mounted on the mounting structure 132, an electroniccomponent 104 of the package 100 is electrically connected to theelectric contact 134 via an electrically conductive carrier 102, hereembodied as a leadframe made of copper, of the package 100.

The package 100 thus comprises the electrically conductive carrier 102,the electronic component 104 (which is here embodied as a powersemiconductor chip) adhesively (see reference numeral 136) mounted onthe carrier 102, and an encapsulant 106 encapsulating part of thecarrier 102 and part of the electronic component 104. As can be takenfrom FIG. 1 , a pad on an upper main surface of the electronic component104 is electrically coupled to the carrier 102 via a bond wire aselectrically conductive contact element 110.

During operation of the power package or package 100, the powersemiconductor chip in form of the electronic component 104 generates aconsiderable amount of heat. At the same time, it shall be ensured thatany undesired current flow between a bottom surface of the package 100and an environment is reliably avoided.

For ensuring electrical insulation of the electronic component 104 andremoving heat from an interior of the electronic component 104 towardsan environment, an electrically insulating and thermally conductiveinterface structure 108 may be provided which covers an exposed surfaceportion of the carrier 102 and a connected surface portion of theencapsulant 106 at the bottom of the package 100. The electricallyinsulating property of the interface structure 108 prevents undesiredcurrent flow even in the presence of high voltages between an interiorand an exterior of the package 100. The thermally conductive property ofthe interface structure 108 promotes a removal of heat from theelectronic component 104, via the electrically conductive carrier 102(of thermally properly conductive copper), through the interfacestructure 108 and towards a heat dissipation body 112. The heatdissipation body 112, which may be made of a highly thermally conductivematerial such as copper or aluminum, has a base body 114 directlyconnected to the interface structure 108 and has a plurality of coolingfins 116 extending from the base body 114 and in parallel to one anotherso as to remove the heat towards the environment.

Although FIG. 1 shows a very specific packaging architecture, the use ofthe encapsulant 106 which will be described below in further detail isadvantageous also for any other packaging architectures of packages 100,etc.

As will be described below referring to FIG. 2 , the encapsulant 106 maybe a ceramic-based inorganic encapsulant material, for instance cement.Moreover, a morphological adhesion promoter 150 may be arranged betweenthe electronic component 104 and the ceramic encapsulant 106, as will bedescribed below referring to FIG. 2 as well.

As indicated schematically by reference numeral 150′ in FIG. 1 , it ispossible that also at least part of the carrier 102 (in particular aportion of the carrier 102 in contact with the encapsulant 106) iscovered by an adhesion promoter such as the adhesion promoter 150covering at least part of the electronic component 104. Additionally oralternatively and as indicated schematically by reference numeral 150″in FIG. 1 , it is also possible that also at least part of theelectrically conductive contact element 110 is covered by an adhesionpromoter such as the adhesion promoter 150 covering at least part of theelectronic component 104. By taking this measure, the stability of thepackage 100 may be further increased and the tendency of delaminationwithin package 100 may be further suppressed.

FIG. 2 schematically illustrates an interface region with morphologicaladhesion promoter 150 between electronic component 104 (for instance,the shown part of the electronic component 104 in FIG. 2 may be a pad,such as an aluminum or copper pad, on a semiconductor body) andinorganic ceramic-based encapsulant 106 according to an exemplaryembodiment.

As already mentioned above, the encapsulant 106 may comprise cement,concrete, or alternatively gypsum or mortar. Such a ceramic-basedinorganic encapsulant 106 may have inherently non-flammable properties,so that the addition of non-flammable additives may be dispensable. Thisrenders the encapsulant 106 simple in manufacture. In particular, thecombination of a morphological adhesion promoter 150 and a ceramicencapsulant 106 may be highly advantageous. This ensures properadhesion, keeps thermomechanical stress small, enables efficient heatremoval, prevents corrosion, and ensures thermal stability in thepresence of very high temperatures.

For instance, the schematically illustrated morphological adhesionpromoter 150 may be a roughened copper structure or a porous Zn/Cr layerhaving pores into which material of the encapsulant 106 (which may be atleast partially liquid or flowable during manufacture) may penetrate.Roughening of a copper material may be accomplished for instance by aplasma treatment, by wet etching, and/or by a mechanical treatment.

As shown in FIG. 2 , the adhesion promoter 150 has a plurality ofopenings 160 in the form of pores with varying diameter. The material ofthe adhesion promoter 150 may be selected for partially or entirelycompensating a mismatch of the coefficient of thermal expansion betweenthe material of the electronic component 104 and the material of theencapsulant 106.

Adhesion promoting interlayer 152 forms an interface between theencapsulant 106 and the adhesion promoter 150. For instance, a verticalthickness, d, of the interlayer 152 can be 100 nm. The interlayer 152constitutes a continuous transient between material of the encapsulant106 and material of the adhesion promoter 150, as will be described inthe following in further detail: For manufacturing the structure shownin FIG. 2 , it may be possible to form the encapsulant 106 on and in theadhesion promoter 150 by providing a mixture of a solution and particlesin the solution, as a precursor of the encapsulant 106. Duringmanufacture of the encapsulant 106, the solution may flow inside thepore type openings 160 of the morphological adhesion promoter 150. Thisliquid phase or flowable matrix may then be cured or solidified (forinstance by hydration or polymerization) and may thus remain in a solidphase permanently within the pores of the morphological adhesionpromoter 150. This results in an encapsulant 106 comprising a solidmatrix 182 (formed on the basis of the previously liquid precursor) andfiller particles 184 embedded in the matrix 182. When the morphologicaladhesion promoter 150 has been formed on the electronic component 104before the encapsulating, it may be possible to contact themorphological adhesion promoter 150 with the solution as one ofprecursors of the encapsulant 106 in such a way that the solutionpenetrates into the openings 160 in the morphological adhesion promoter150.

With the structure shown in FIG. 2 , it may be possible to combineproper adhesion promotion, reliable stress suppression, and provision ofa strong corrosion barrier.

Still referring to FIG. 2 , the morphological adhesion promoter 150defining interlayer 152 is arranged to increase the adhesion betweenencapsulant 106 and electronic component 104, reduce or smoothen a CTEmismatch between encapsulant 106 and chip 102 and suppress undesiredcorrosion. For this purpose, the morphological adhesion promoter 150comprises the openings 160 with decreasing diameter from a region inwhich the package 100 purely consists of encapsulant material up to theelectronic component 104. Thus, a liquid precursor used formanufacturing the ceramic-based encapsulant 106 may flow into theopenings 160 during the manufacturing process and may contribute to asmooth transition of the coefficient of thermal expansion (CTE) along avertical or z-axis direction which is indicated with reference numeral190 in FIG. 2 . At a vertical level 192, the CTE value is defined bymaterial of the encapsulant 106 only. At a level 194, the CTE value isdefined by material (in particular aluminum of a pad or silicon materialof a semiconductor body) of the electronic component 104 only. However,from a vertical level of layer 198 up to another vertical level of layer196, the amount of material provided by the encapsulant 106 continuouslydecreases while an amount of material of the adhesion promoter 150continuously increases. While at vertical level 198, the CTE value isdominated by material of encapsulant 106, the CTE value is dominated bymaterial of the adhesion promoter 150 at level 196. For instance, theporosity (i.e. a ratio between pore volume on the one hand and the sumof pore volume and solid adhesion promoter material volume on the otherhand) of the interlayer 152 may be 10% at layer 196, whereas theporosity may be 90% at layer 198. In particular, variation andadjustment of porosity of morphological adhesion promoter 150 by tuningits morphology allows for a smooth CTE transition, compared to thermalmechanically disadvantageous jump functions of CTE at an abruptinterface between encapsulant 106 and electronic component 104. As aresult, the CTE mismatch is smoothly changed along direction 190, whichreduces thermal load inside of the package 100. Additionally, themorphology of the morphological adhesion promoter 150 promotesmechanical interlocking between encapsulant material and adhesionpromoter material and increases the interior surface so as to enhanceadhesion between material of encapsulant 106 and material of electroniccomponent 104. By properly selecting the material of the adhesionpromoter 150 and of the encapsulant 106, also the tendency of thepackage 100 of corroding during use in humid environment can be stronglysuppressed. Therefore, a highly reliably package 100 can be obtained byan exemplary embodiment.

The cement of the ceramic-based encapsulant 106 may reducethermomechanical stress due to its highly advantageous CTE properties.Furthermore, the cement material with its crystalline structure mayenhance mechanical stability of the package 100. Even more important,thermal stability of cement increases manufacturing and operationtemperatures of the package 100 compared to conventional approaches.Moreover, cement material has an excellent thermal conductivity, ascompared to other encapsulation materials.

In particular in combination with the morphological adhesion promoter150, an improved adhesion and a reduced tendency of delamination, aswell as an increased tensile strength of the package 100 may beobtained.

A skilled person will understand that the illustration of the porestructure in FIG. 2 is merely schematic and for illustrative purposes.The geometry of such a pore structure may broadly vary depending on theused materials and used processes.

In the following, different embodiments of deposition layer porositywill be compared:

FIG. 3 is a plan view of a morphological adhesion promoter 150 accordingto an exemplary embodiment comprising manganite. A flat structure isobtained, no pores.

FIG. 4 is a plan view of a morphological adhesion promoter 150 accordingto an exemplary embodiment comprising zinc-chromium alloy and oxide onNiP. FIG. 5 is a cross-sectional view of the morphological adhesionpromoter 150 according to FIG. 4 . The shown embodiment corresponds to aporous structure on NiP. A sponge-like structure is obtained withfeatures of characteristic size larger than 30 nm.

FIG. 6 is a plan view of a morphological adhesion promoter 150 accordingto an exemplary embodiment comprising zinc vanadium alloy and oxide. Theshown embodiment corresponds to ZnV on NiP. FIG. 7 is a cross-sectionalview of the morphological adhesion promoter 150 according to FIG. 6 . Astructure with porous plates is obtained with features of characteristicsize in a range between 5 nm and 50 nm.

FIG. 8 is a plan view of a morphological adhesion promoter 150 accordingto an exemplary embodiment comprising zinc molybdenum alloy and oxide.The shown embodiment corresponds to ZnMo on NiP. A crystal structure isobtained with features of characteristic size much smaller than 30 nm

FIG. 9 is a plan view of a morphological adhesion promoter 150 accordingto an exemplary embodiment comprising zinc-vanadium (Zn—V) on NiP. FIG.10 is a cross-sectional view of the morphological adhesion promoter 150according to FIG. 9 . FIG. 11 shows a detail of the cross-sectional viewof FIG. 10 . FIG. 12 shows a detail of the cross-sectional view of FIG.11 . FIG. 13 shows a further detail of the morphological adhesionpromoter 150 according to FIG. 9 to FIG. 12 . The thickness of themorphological adhesion promoter 150 is about 200 nm. Zn dendrites orcrystallites with typical dimensions in the range between 10 nm and 20mm are obtained. A porous shell of vanadium oxide with zinc traces mayhave typical dimensions in a range between 10 nm and 20 nm. A shell poresize may be smaller than 10 nm. A seed layer of vanadium oxide with zinctraces may have dimensions of 20 nm.

FIG. 14 illustrates a model of a porous morphological adhesion promoter150 according to an exemplary embodiment. FIG. 15 is a diagramillustrating a stress mean value (vertical axis of the diagram) alongthe vertical direction (horizontal axis of the diagram) of the porousmorphological adhesion promoter 150 according to FIG. 14 . FIG. 16 is adiagram illustrating a stress mean value along the vertical directionwithout porous morphological adhesion promoter, for comparison with FIG.15 . Thus, FIG. 15 shows the stress minimized with porous adhesionpromoter, and FIG. 16 is the reference of non-stress minimized withoutthe porous adhesion promoter. FIG. 14 and FIG. 15 prove the compensationof the CTE (coefficient of thermal expansion) mismatch and the stressreduction obtained by exemplary embodiments.

The simulated morphological adhesion promoter 150 shows that theconfiguration of FIG. 15 may result in a stress reduction and anadaptation of the coefficient of thermal expansion. More specifically,the illustrated simulation shows that the porous morphological adhesionpromoter 150 acts as stress reduction at an interface between a moldcompound and an electronic component. For instance, the stress may bereduced from 0.3 GPa to about 0.1 GPa, i.e. a factor of three of stressreduction at the interface between copper and mold compound may beachieved.

It should be noted that the term “comprising” does not exclude otherelements or features and the “a” or “an” does not exclude a plurality.Also, elements described in association with different embodiments maybe combined. It should also be noted that reference signs shall not beconstrued as limiting the scope of the claims. Moreover, the scope ofthe present application is not intended to be limited to the particularembodiments of the process, machine, manufacture, composition of matter,means, methods and steps described in the specification. Accordingly,the appended claims are intended to include within their scope suchprocesses, machines, manufacture, compositions of matter, means,methods, or steps.

What is claimed is:
 1. A package, comprising: an electronic component;an inorganic encapsulant encapsulating at least part of the electroniccomponent; and an adhesion promoter that enhances adhesion between atleast part of the electronic component and the encapsulant, wherein theadhesion promoter is a morphological adhesion promoter comprising amorphological structure having a plurality of openings.
 2. The packageof claim 1, wherein the encapsulant is a ceramic-based encapsulant or aninorganic polymer-based encapsulant.
 3. The package of claim 1, whereinthe encapsulant comprises at least one selected from the groupconsisting of: cement, concrete, gypsum, mortar, a silicon polymer, andan aluminum polymer.
 4. The package claim 1, wherein the morphologicaladhesion promoter comprises at least one selected from the groupconsisting of: a metallic structure, an alloy structure, an alloy oxidestructure, a chromium structure, a vanadium structure, a molybdenumstructure, a zinc structure, a manganese structure, a cobalt structure,a nickel structure, a copper structure, a flame deposited structure, aroughened metal structure, and any alloy, alloy oxide, oxide, nitride,carbide, and selenide of said structures.
 5. The package claim 1,wherein the plurality of openings comprises at least one selected fromthe group consisting of: pores, dendrites, and gaps between islands of apatterned structure.
 6. The package of claim 1, wherein a material ofthe adhesion promoter is adapted for at least partially compensating amismatch between the coefficients of thermal expansion of a material ofthe electronic component and a material of the encapsulant.
 7. Thepackage of claim 1, wherein the adhesion promoter forms an interlayer inan interface region between the encapsulant and the electroniccomponent.
 8. The package of claim 7, wherein at least one of: theinterlayer provides a transition of porosity between the encapsulant andthe electronic component; at least part of pores of the interlayer areat least partially filled with material of the encapsulant; and theinterlayer has a thickness in a range between 30 nm and 500 nm.
 9. Thepackage of claim 1, further comprising a carrier on which the electroniccomponent is mounted, wherein the carrier is at least partiallyencapsulated in the encapsulant, and wherein the carrier is at leastpartially covered by an adhesion promoter.
 10. The package of claim 9,further comprising an electrically conductive contact elementelectrically coupling the electronic component with the carrier, whereinthe electrically conductive contact element is at least partiallyencapsulated in the encapsulant, and wherein the electrically conductivecontact element is at least partially covered by an adhesion promoter.11. The package of claim 1, wherein the electronic component comprisesat least one selected from the group consisting of: a semiconductorchip, a power semiconductor chip, an active electronic device, a passiveelectronic device, a sensor, an actuator, and a microelectromechanicalsystem.
 12. The package of claim 9, wherein the carrier is a leadframemade of copper.
 13. The package of claim 10, wherein the electricallyconductive contact element is a bond wire.
 14. The package of claim 1,wherein the electronic component is a semiconductor chip having a metalpad.
 15. The package of claim 14, wherein the metal pad is an aluminumor copper pad.
 16. The package of claim 14, wherein along a verticaldirection perpendicular to the metal pad, a coefficient of thermalexpansion of the package is dominated by the encapsulant at a firstvertical level, dominated by the metal pad at a second level, anddominated by the adhesion promoter at a third level between the firstlevel and the second level.
 17. The package of claim 14, wherein along avertical direction perpendicular to the metal pad, an amount of materialprovided by the encapsulant continuously decreases and an amount ofmaterial provided by the adhesion promoter continuously increasesbetween a first vertical level and a second vertical level, the secondvertical level being closer to the metal pad than the first verticallevel.